We are doing connect nodejs with mysql.

const mysql = require('mysql');

const con = mysql.createConnection({
    host:'localhost',
    user:"root",
    password:"",
    database:"node"
});

con.connect((err)=>{
   if(err)
   {
    console.log("Error")
   }else{
    console.log("Connected")
   }
})

con.query("select * from users",(err,result)=>{
    console.warn("result",result)
})

We connecting nodejs with mongodb database.

const {MongoClient} = require('mongodb');
const url = 'mongodb://localhost:27017';
const database = 'ecommerce'
const client = new MongoClient(url);

async function dbConnect() {
    let result = await client.connect();
    let db = result.db(database);
    return db.collection('products');
    // let response = await collection.find({Name:'smart redmi Phone'}).toArray();
    // console.log(response);
    
}

// dbConnect().then((response)=>{
//     response.find().toArray().then((data)=>{
//         console.warn(data)
//     })
// })

const main = async ()=>{
    let data = await dbConnect();
    data = await data.find().toArray();
    console.warn(data)
}

main();

We creating a new file.

var fs = require('fs');

//create a file named mynewfile3.txt:
fs.writeFile('mynewfile3.txt', 'Hello content!', function (err) {
  if (err) throw err;
  console.log('Saved!');
});

              

We creating basic api.

var http = require('http');

http.createServer((req, res) => {
    res.writeHead(200, {'Content-Type': 'application\json'});
    res.write(JSON.stringify({name:'krishna',email:'krishna@gmail.com'}));
    res.end();
}).listen(8000);

We creating mysql api.

const express = require('express');
const con = require('./config_mysql');
const app = express();

app.use(express.json());

app.get('/',(req,res)=>{
    con.query("select * from users",(err,result)=>{
        if(err){
            res.send("error")
        }else{
            res.send(result)
        }
    })
});

app.post('/',(req,res)=>{
    const data = req.body;
    con.query("INSERT INTO users set?",data,(error,results,fields)=>{
        if(error) error;
        res.send(results)
    })
})

app.put('/:id',(req,res)=>{
    const data = [req.body.name,req.body.email,req.body.password,req.params.id];
    con.query("UPDATE users set name = ?, email = ?, password = ? where id = ?",data,(error,results,fields)=>{
        if(error) throw error;
        res.send(results)
    })
})

app.delete('/:id',(req,res)=>{
    con.query("DELETE FROM users WHERE id =" + req.params.id,(error,results)=>{
        if(error) throw error;
        res.send(results)
    })
})

app.listen(5000);

We creating a server.

var http = require('http');

http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World!');
}).listen(8080);